1. Field of the Invention
The present invention relates generally to an apparatus and method for transmitting and receiving data in a multiuser Multiple-Input Multiple-Output (MIMO) system, and in particular, to an apparatus and method for transmitting and receiving data in a multiuser MIMO system in which a base station adaptively selects an antenna scheduling scheme.
2. Description of the Related Art
The existing wireless mobile communication systems provide voice-oriented services and mostly depend on channel coding to overcome any inferiority of channels. However, due to the increasing demands for a high-quality multimedia service in which users can communicate with anyone regardless of time and place, the existing services are evolving into data-oriented services. Accordingly, there is a high demand for next generation wireless transmission technology for transmitting the larger amount of data at a lower error rate. In particular, it is very important to transmit data at a high rate in a link in which the amount of required data is large.
For the next generation wireless communication, various antenna systems have been proposed. For example, a MIMO system, i.e., a typical antenna system, increases spectrum efficiency through all of transmission antennas without excessive use of a frequency bandwidth. Generally, MIMO is classified into Space-Time Coding (STC), Diversity, Beam Forming (BF), and Spatial Multiplexing (SM) according to the transmission structure and scheme of a transmitter, all of which provide high data rate and reliability.
When various antenna systems are used in a transmission side or a reception side, a scheduling scheme serves as the most important factor in determining system capacity in a multiuser MIMO environment in which different transmission antennas can be simultaneously allocated for data transmission of specific users. As cellular networks tend to use the increasing number of transmission/reception antennas and service the increasing number of users, a scheduling algorithm plays an important role in complicated system scenarios.
A transmission antenna scheduling scheme for users includes various resource (i.e., transmission antennas) allocation schemes. For example, all of transmission antennas are allocated to one user, or the transmission antennas are allocated to different users according to link conditions between the transmission antennas and reception antennas.
The reception side is implemented with linear Zero-Forcing (ZF), Minimum Mean-Squared Error (MMSE), Successive Interference Cancellation (SIC), Ordered SIC, Sphere Decoding, and Maximum Likelihood, and an increase in performance of those schemes undesirably increases complexity of the implementation.
Therefore, in the wireless communication system, the best system capacity is determined according to the type of the MIMO system, the type of the scheduling scheme, and the implementation method of the reception side. Accordingly, the implementation can be achieved in different manners according to purposes of the system.